[Propofol and postoperative nausea and/or vomiting].

UNLABELLED: The objective of this prospective, randomised study was to investigate the incidence of postoperative nausea and/or vomiting (PONV) during the first 24 h postoperatively. For a quality assurance study on PONV, we compared two established general anaesthetic procedures in 239 patients undergoing four different types of surgery (subtotal thyroidectomy, laparotomy for gynaecological procedures, laparoscopy, and surgery for extra-abdominal procedures).

METHODS: All eligible patients provided informed consent. For premedication temazepam 10-20 mg was administered orally. We used propofol (1.5-2 mg/kg) for induction of anaesthesia in all patients, followed by 0.1-0.3 mg fentanyl, 2.5-5 mg droperidol, and for muscular relaxation atracurium or pancuronium according to body weight. Maintenance of general anaesthesia in group A was by administration of isoflurane in a maximum concentration of 0.6 vol.% in 70% nitrous oxide and 30% oxygen and in group B by continuous infusion of propofol (5-8 mg/kg.h) and normoventilation with oxygen in air (Fi02 = 0.3). In both groups additional analgesia was provided intraoperatively by equal dosages of fentanyl up to a maximum of 0.6 mg and clonidine up to 200 micrograms. Episodes of PONV were registered following extubation, during the first 4 h postoperatively, during the period 4-24 h postoperatively, and after the first mobilisation. Pain scores were recorded with the aid of a visual analogues scale. The statistical evaluation was performed using the chi-square or Wilcoxon test.

RESULTS AND DISCUSSION: In patients undergoing thyroidectomy or laparotomy, continuous infusion of propofol drastically reduced the incidence of PONV in the first 24 h postoperatively, particularly during the first 4 h (25/41 vs 10/41, resp. 20/32 vs 11/31). The overall incidence of PONV was higher in the first half of the menstrual cycles decreased with patient age, increased with the duration of anaesthesia, and was higher in patients with a history of motion sickness. With the same level of analgesia in both groups, the differences disappeared in the further postoperative course. The use of similar dosages of opioids for pain control in these groups might explain this observation. PONV occurred extremely rarely in patients undergoing laparoscopy (1 resp. 2 of 34), and in those undergoing surgery for extra-abdominal procedures did not occur at all. The explanation may be that the induction of anaesthesia with propofol was followed only by a relatively short duration of general anaesthesia for these surgical procedures, and postoperative pain control was performed solely with non-opioids.

CONCLUSIONS: We found that the antiemetic effect of propofol was considerable in the early postoperative period. The higher cost of propofol as compared to other induction agents can be covered by not using nitrous oxide for maintenance of anaesthesia and by the decreased need for antiemetic drugs postoperatively. According to the calculations of our clinical pharmacy, the costs of the propofol infusion regimen exceeded those of balanced anaesthesia by 8.50 DM/h; the need for antiemetics was one-half that of the non-propofol group. Considering a cost of 16 DM for cleaning the bed after vomiting, improvement of the patient's condition during the postoperative period can be achieved without additional expense.